Abstract:

There is provided a semiconductor light emitting device, a method of
manufacturing the same, and a semiconductor light emitting device package
using the same. A semiconductor light emitting device having a first
conductivity type semiconductor layer, an active layer, a second
conductivity type semiconductor layer, a second electrode layer, and
insulating layer, a first electrode layer, and a conductive substrate
sequentially laminated, wherein the second electrode layer has an exposed
area at the interface between the second electrode layer and the second
conductivity type semiconductor layer, and the first electrode layer
comprises at least one contact hole electrically connected to the first
conductivity type semiconductor layer, electrically insulated from the
second conductivity type semiconductor layer and the active layer, and
extending from one surface of the first electrode layer to at least part
of the first conductivity type semiconductor layer.

Claims:

1. A semiconductor light emitting device having a first conductivity type
semiconductor layer, an active layer, a second conductivity type
semiconductor layer, a second electrode layer, and insulating layer, a
first electrode layer, and a conductive substrate sequentially
laminated,wherein the second electrode layer has an exposed area at the
interface between the second electrode layer and the second conductivity
type semiconductor layer, andthe first electrode layer comprises at least
one contact hole electrically connected to the first conductivity type
semiconductor layer, electrically insulated from the second conductivity
type semiconductor layer and the active layer, and extending from one
surface of the first electrode layer to at least part of the first
conductivity type semiconductor layer.

2-18. (canceled)

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims the priority of Korean Patent Application
No. 10-2007-0105365 filed on Oct. 19, 2007, in the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by
reference.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates to a semiconductor light emitting
device, a method of manufacturing the same, and a semiconductor light
emitting device package using the same, and more particularly, to a
semiconductor light emitting device that ensures a maximum light emitting
area to maximize luminous efficiency and perform uniform current
spreading by using an electrode having a small area, and enables mass
production at low cost with high reliability and high quality, a method
of manufacturing the same, and a semiconductor light emitting device
package using the same.

[0004]2. Description of the Related Art

[0005]Semiconductor light emitting devices include materials that emit
light. For example, light emitting diodes (LEDs) are devices that use
diodes, to which semiconductors are bonded, convert energy generated by
combination of electrons and holes into light, and emit light. The
semiconductor light emitting devices are being widely used as lighting,
display devices, and light sources, and development of semiconductor
light emitting devices has been expedited.

[0006]In particular, the widespread use of cellular phone keypads, side
viewers, and camera flashes, which use GaN-based light emitting diodes
that have been actively developed and widely used in recent years,
contribute to the active development of general illumination that uses
light emitting diodes. Applications of the light emitting diodes, such as
backlight units of large TVs, headlights of cars, and general
illumination, have advanced from small portable products to large
products having high power, high efficiency, and high reliability.
Therefore, there has been a need for light sources that have
characteristics required for the corresponding products.

[0007]In general, a semiconductor junction light emitting device has a
structure in which p-type and n-type semiconductors are bonded to each
other. In the semiconductor junction structure, light may be emitted by
recombination of electrons and holes at a region where the two types of
semiconductors are bonded to each other. In order to activate the light
emission, an active layer may be formed between the two semiconductors.
The semiconductor junction light emitting device includes a horizontal
structure and a vertical structure according to the position of
electrodes of semiconductor layers. The vertical structure includes an
epi-up structure and a flip-chip structure. As described above,
structural characteristics of semiconductor light emitting devices that
are required according to characteristics of individual products are
seriously taken into account.

[0008]FIGS. 1A and 1B are views illustrating a horizontal light emitting
device according to the related art. FIG. 1c is a cross-sectional view
illustrating a vertical light emitting device according to the related
art. Hereinafter, for the convenience of explanation, in FIGS. 1A to 1C,
a description will be made on the assumption that an n-type semiconductor
layer is in contact with a substrate, and a p-type semiconductor layer is
formed on an active layer.

[0009]Referring to FIG. 1A, a horizontal light emitting device having an
epi-up structure will be described first. In FIG. 1A, a description will
be made on the assumption that a semiconductor layer formed at the
outermost edge is a p-type semiconductor layer. A semiconductor light
emitting device 1 includes a non-conductive substrate 13, an n-type
semiconductor layer 12, an active layer 11, and a p-type semiconductor
layer 10. An n-type electrode 15 and a p-type electrode 14 are formed on
the n-type semiconductor layer 12 and the p-type semiconductor layer 10,
respectively, and are connected to an external current source (not shown)
to apply a voltage to the semiconductor light emitting device 1.

[0010]When a voltage is applied to the semiconductor light emitting device
1 through the electrodes 14 and 15, electrons move from the n-type
semiconductor layer 12, and holes move from the p-type semiconductor
layer 10. Light is emitted by recombination of the electrons and the
holes. The semiconductor light emitting device 1 includes the active
layer 11, and light is emitted from the active layer 11. In the active
layer 11, the light emission of the semiconductor light emitting device 1
is activated, and light is emitted. In order to make an electrical
connection, the n-type electrode and the p-type electrode are located on
the n-type semiconductor layer 12 and the p-type semiconductor layer 10,
respectively, with the lowest contact resistances.

[0011]The position of the electrodes may change according to the substrate
type. For example, when the substrate 13 is a sapphire substrate that is
a non-conductive substrate, the electrode of the n-type semiconductor
layer 12 cannot be formed on the non-conductive substrate 13, but on the
n-type semiconductor layer 12.

[0012]Therefore, referring to FIG. 1A, when the n-type electrode 15 is
formed on the n-type semiconductor 12, parts of the p-type semiconductor
layer 10 and the active layer 12 that are formed at the upper side are
consumed to form an ohmic contact. The formation of the electrode results
in a decrease of light emitting area of the semiconductor light emitting
device 1, and thus luminous efficiency also decreases.

[0014]The semiconductor light emitting device, shown in FIG. 1B, is a flip
chip semiconductor light emitting device 2. A substrate 23 is located at
the top. Electrodes 24 and 25 are in contact with electrode contacts 26
and 27, respectively, which are formed on a conductive substrate 28.
Light emitted from an active layer 21 is emitted through the substrate 23
regardless of the electrodes 24 and 25. Therefore, the decrease in
luminous efficiency that is caused in the semiconductor light emitting
device, shown in FIG. 1A, can be prevented.

[0015]However, despite the high luminous efficiency of the flip chip light
emitting device 2, the n-type electrode and the p-type electrode in the
light emitting device 2 need to be disposed in the same plane and bonded
in the semiconductor light emitting device 2. After being bonded, the
n-type electrode and the p-type electrode are likely to be separated from
the electrode contacts 26 and 27. Therefore, there is a need for
expensive precision processing equipment. This causes an increase in
manufacturing costs, a decrease in productivity, a decrease in yield, and
a decrease in product reliability.

[0016]In order to solve a variety of problems including the
above-described problems, a vertical light emitting device that uses a
conductive substrate, not the non-conductive substrate, appeared. A light
emitting device 3, shown in FIG. 1c, is a vertical light emitting device.
When a conductive substrate 33 is used, an n-type electrode 35 may be
formed on the substrate 33. The conductive substrate 33 may be formed of
a conductive material, for example, Si. In general, it is difficult to
form semiconductor layers on the conductive substrate due to
lattice-mismatching. Therefore, semiconductor layers are grown by using a
substrate that allows easy growth of the semiconductor layers, and then a
conductive substrate is bonded after removing the substrate for growth.

[0017]When the non-conductive substrate is removed, the conductive
substrate 33 is formed on the n-type semiconductor layer 32, such that
the light emitting device 3 has a vertical structure. When the conductive
substrate 33 is used, since a voltage can be applied to the n-type
semiconductor layer 32 through the conductive substrate 33, an electrode
can be formed on the substrate 33. Therefore, as shown in FIG. 1c, the
n-type electrode 35 is formed on the conductive substrate 33, and the
p-type electrode 34 is formed on the p-type semiconductor layer 30, such
that the semiconductor light emitting device having the vertical
structure can be manufactured.

[0018]However, when a high-power light emitting device having a large area
is manufactured, an area ratio of the electrode to the substrate needs to
be high for current spreading. Therefore, light extraction is limited,
light loss is caused by optical absorption, luminous efficiency
decreases, and product reliability is reduced.

SUMMARY OF THE INVENTION

[0019]An aspect of the present invention provides to a semiconductor light
emitting device that ensures a maximum light emitting area to maximize
luminous efficiency and perform uniform current spreading by using an
electrode having a small area, and enables mass production at low cost
with high reliability and high quality, a method of manufacturing the
same, and a semiconductor light emitting device package using the same.

[0020]According to an aspect of the present invention, there is provided a
semiconductor light emitting device having a first conductivity type
semiconductor layer, an active layer, a second conductivity type
semiconductor layer, a second electrode layer, and insulating layer, a
first electrode layer, and a conductive substrate sequentially laminated,
wherein the second electrode layer has an exposed area at the interface
between the second electrode layer and the second conductivity type
semiconductor layer, and the first electrode layer comprises at least one
contact hole electrically connected to the first conductivity type
semiconductor layer, electrically insulated from the second conductivity
type semiconductor layer and the active layer, and extending from one
surface of the first electrode layer to at least part of the first
conductivity type semiconductor layer.

[0021]The semiconductor light emitting device may further include an
electrode pad unit formed at the exposed area of the second electrode
layer.

[0022]The exposed area of the second electrode layer may be a region
exposed by a via hole formed through the first conductivity type
semiconductor layer, the active layer, and the second conductivity type
semiconductor layer.

[0023]The diameter of the via hole may increase in a direction from the
second electrode layer toward the first conductivity type semiconductor
layer.

[0024]An insulating layer may be formed on an inner surface of the via
hole.

[0025]The exposed area of the second electrode layer may be formed at the
edge of the semiconductor light emitting device.

[0026]The second electrode layer may reflect light generated from the
active layer.

[0027]The second electrode layer may include one metal selected from a
group consisting of Ag, Al, and Pt.

[0028]An irregular pattern may be formed on the surface of the first
conductivity type semiconductor layer.

[0029]The irregular pattern may have a photonic crystal structure.

[0030]The conductive substrate may include one metal selected from a group
consisting of Au, Ni, Cu, and W.

[0031]The conductive substrate may include one selected from a group
consisting of Si, Ge, and GaAs.

[0032]According to another aspect of the present invention, there is
provided a method of manufacturing a semiconductor light emitting device,
the method including: sequentially laminating a first conductivity type
semiconductor layer, an active layer, a second conductivity type
semiconductor layer, a second electrode layer, an insulating layer, a
first electrode layer, and a conductive substrate; forming an exposed
area at the interface between the second electrode layer and the second
conductivity type semiconductor layer; and forming at least one contact
hole in the first electrode layer, the contact hole electrically
connected to the first conductivity type semiconductor layer,
electrically insulated from the second conductivity type semiconductor
layer and the active layer, and extending from one surface of the first
electrode layer to at least part of the first conductivity type
semiconductor layer.

[0033]The forming an exposed area of the second electrode layer may
include mesa etching the first conductivity type semiconductor layer, the
active layer, and the second conductivity type semiconductor layer.

[0034]The conductive substrate may be formed by plating method and
laminated. The conductive substrate may be laminated by a substrate
bonding method.

[0035]According to still another aspect of the present invention, there is
provided a semiconductor light emitting device package including: a
semiconductor light emitting device package body having a recessed part
formed at an upper surface thereof; a first lead frame and a second lead
frame mounted to the semiconductor light emitting device package body,
exposed at a lower surface of the recessed part, and separated from each
other by a predetermined distance; a semiconductor light emitting device
mounted to the first lead frame, wherein the semiconductor light emitting
device has a first conductivity type semiconductor layer, an active
layer, a second conductivity type semiconductor layer, a second electrode
layer, an insulating layer, a first electrode layer, and a conductive
substrate sequentially laminated, the second electrode layer comprises an
exposed area at the interface between the second electrode layer and the
second conductivity type semiconductor layer, and the first electrode
layer comprises at least one contact hole electrically connected to the
first conductivity type semiconductor layer, electrically insulated from
the second conductivity type semiconductor layer and the active layer,
and extending from one surface of the first electrode layer to at least
part of the first conductivity type semiconductor layer.

[0036]The semiconductor light emitting device may further include an
electrode pad unit formed at the exposed area of the second electrode
layer, and the electrode pad unit is electrically connected to the second
lead frame.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]The above and other aspects, features and other advantages of the
present invention will be more clearly understood from the following
detailed description taken in conjunction with the accompanying drawings,
in which:

[0043]FIG. 4A is a cross-sectional view illustrating the semiconductor
light emitting device, shown in FIG. 3, taken along the line A-A'.

[0044]FIG. 4B is a cross-sectional view illustrating the semiconductor
light emitting device, shown in FIG. 3, taken along the line B-B'.

[0045]FIG. 4c is a cross-sectional view illustrating the semiconductor
light emitting device, shown in FIG. 3, taken along the line C-C'.

[0046]FIG. 5 is a view illustrating light emission in the semiconductor
light emitting device having an irregular pattern at the surface thereof
according to the embodiment of the present invention.

[0047]FIG. 6 is a view illustrating a second electrode layer exposed at
the edge of the semiconductor light emitting device according to another
embodiment of the present invention.

[0048]FIG. 7 is a cross-sectional view illustrating a semiconductor light
emitting package according to still another embodiment of the present
invention.

[0049]FIG. 8 is a graph illustrating the relationship between luminous
efficiency and current density of a light emitting surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0050]Exemplary embodiments of the present invention will now be described
in detail with reference to the accompanying drawings. The invention may
however be embodied in many different forms and should not be construed
as limited to the embodiments set forth herein. Rather, these embodiments
are provided so that this disclosure will be thorough and complete, and
will fully convey the scope of the invention to those skilled in the art.

[0051]FIG. 2 is a perspective view illustrating a semiconductor light
emitting device according to an exemplary embodiment of the invention.
FIG. 3 is a plan view illustrating the semiconductor light emitting
device shown in FIG. 2. Hereinafter, a description will be made with
reference to FIGS. 2 and 3.

[0052]A semiconductor light emitting device 100 according to the exemplary
embodiment of the invention includes a first conductivity type
semiconductor layer 111, an active layer 112, a second conductivity type
semiconductor layer 113, a second electrode layer 120, a first insulating
layer 130, a first electrode layer 140, and a conductive substrate 150
that are sequentially laminated. At this time, the second electrode layer
120 has an exposed area at the interface between the second electrode
layer 120 and the second conductivity type semiconductor layer 113. The
first electrode layer 140 includes at least one contact hole 141. The
contact hole 141 is electrically connected to the first conductivity type
semiconductor layer 111, electrically insulated from the second
conductivity type semiconductor layer 113 and the active layer 112, and
extends from one surface of the first electrode layer 140 to at least
part of the first conductivity type semiconductor layer 111.

[0053]In the semiconductor light emitting device 100, the first
conductivity type semiconductor layer 111, the active layer 112, and the
second conductivity type semiconductor layer 113 perform light emission.
Hereinafter, they are referred to as a light emitting lamination 110.
That is, the semiconductor light emitting device 100 includes the light
emitting lamination 110, the first electrode layer 140, and the first
insulating layer 130. The first electrode layer 140 is electrically
connected to the first conductivity type semiconductor layer 111. The
second electrode layer 120 is electrically connected to the second
conductivity type semiconductor layer 113. The first insulating layer 130
electrically insulates the electrode layers 120 and 140 from each other.
Further, the conductive substrate 150 is included as a substrate to grow
or support the semiconductor light emitting device 100.

[0054]Each of the semiconductor layers 111 and 113 may be formed of a
semiconductor, such as a GaN-based semiconductor, a ZnO-based
semiconductor, a GaAs-based semiconductor, a GaP-based semiconductor, and
a GaAsP-based semiconductor. The semiconductor layer may be formed by
using, for example, molecular beam epitaxy (MBE). In addition, each of
the semiconductor layers may be formed of any one of semiconductors, such
as a III-V semiconductor, a II-VI semiconductor, and Si. Each of the
semiconductor layers 111 and 113 is formed by doping the above-described
semiconductor with appropriate impurities in consideration of the
conductivity type.

[0055]The active layer 112 is a layer where light emission is activated.
The active layer 112 is formed of a material that has a smaller energy
bandgap than each of the first conductivity type semiconductor layer 111
and the second conductivity type semiconductor layer 113. For example,
when each of the first conductivity type semiconductor layer 111 and the
second conductivity type semiconductor layer 113 is formed of a GaN-based
compound, the active layer 112 may be formed by using an InAlGaN-based
compound semiconductor that has a smaller energy bandgap than GaN. That
is, the active layer 112 may include InxAlyGa.sub.(1-x-y)N
(0≦c≦1, 0≦y≦1, 0≦x+y≦1).

[0056]In consideration of characteristics of the active layer 112, the
active layer 120 is preferably not doped with impurities. A wavelength of
light emitted can be controlled by adjusting a mole ratio of
constituents. Therefore, the semiconductor light emitting device 100 can
emit any one of infrared light, visible light, and UV light according to
the characteristics of the active layer 112.

[0057]Each of the electrode layers 120 and 140 is formed in order to apply
a voltage to the same conductivity type semiconductor layer. Therefore,
in consideration of electroconductivity, the electrode layers 120 and 140
may be formed of metal. That is, the electrode layers 120 and 140 include
electrodes that electrically connect the semiconductor layers 111 and 113
to an external current source (not shown). The electrode layers 120 and
140 may include, for example, Ti as an n-type electrode, and Pd or Au as
a p-type electrode.

[0058]The first electrode layer 140 is connected to the first conductivity
type semiconductor layer 111, and the second electrode layer 120 is
connected to the second conductivity type semiconductor layer 113. That
is, since the first and second layers 140 and 120 are connected to the
different conductivity type semiconductor layers from each other, the
first and second layers 140 and 120 are electrically separated from each
other by the first insulating layer 130. Preferably, the first insulating
layer 130 is formed of a material having low electroconductivity. The
first insulating layer 130 may include, for example, an oxide such as
SiO2.

[0059]Preferably, the second electrode layer 120 reflects light generated
from the active layer 112. Since the second electrode layer 120 is
located below the active layer 112, the second electrode layer 120 is
located at the other side of a direction in which the semiconductor light
emitting device 100 emits light on the basis of the active layer 112.
Light moving from the active layer 112 toward the second electrode layer
120 is in an opposition direction to the direction in which the
semiconductor light emitting device 100 emits light. Therefore, the light
proceeding toward the second electrode layer 120 needs to be reflected to
increase luminous efficiency. Therefore, when the second electrode layer
120 has light reflectivity, the reflected light moves toward a light
emitting surface to thereby increase the luminous efficiency of the
semiconductor light emitting device 100.

[0060]In order to reflect the light generated from the active layer 112,
preferably, the second electrode layer 120 is formed of metal that
appears white in the visible ray region. For example, the white metal may
be any one of Ag, Al, and Pt.

[0061]The second electrode layer 120 includes an exposed area at the
interface between the second electrode layer 120 and the second
conductivity type semiconductor layer 113. A lower surface of the first
electrode layer 140 is in contact with the conductive substrate 150, and
the first electrode layer 140 is electrically connected to the external
current source (not shown) through the conductive substrate 150. However,
the second electrode layer 120 requires a separate connecting region so
as to be connected to the external current source (not shown). Therefore,
the second electrode layer 120 includes an area that is exposed by
partially etching the light emitting lamination 110.

[0062]In FIG. 2, an example of a via hole 114 is shown. The via hole 114
is formed by etching the center of the light emitting lamination 110 to
form an exposed area of the second electrode layer 120. An electrode pad
unit 160 may be further formed at the exposed area of the second
electrode layer 120. The second electrode layer 120 can be electrically
connected to the external power source (not shown) by the exposed region
thereof . At this time, the second electrode layer 120 is electrically
connected to the external power source (not shown) by using the electrode
pad unit 160. The second electrode layer 120 can be electrically
connected to the external current source (not shown) by a wire or the
like. For convenient connection to the external current source,
preferably, the diameter of the via hole increases from the second
electrode layer toward the first conductivity type semiconductor layer.

[0063]The via hole 114 is formed by selective etching. In general, the
light emitting lamination 110 including the semiconductors is only
etched, and the second electrode layer 120 including the metal is not
etched. The diameter of the via hole 114 can be appropriately determined
by those skilled in the art in consideration of the light emitting area,
electrical connection efficiency, and current spreading in the second
electrode layer 120.

[0064]The first electrode layer 140 includes at least one contact hole
141. The contact hole 141 is electrically connected to the first
conductivity type semiconductor layer 111, electrically insulated from
the second conductivity type semiconductor layer 113 and the active layer
112, and extends to at least part of the first conductivity type
semiconductor layer 111. The first electrode layer 140 includes at least
one contact hole 141 in order to connect the first conductivity type
semiconductor layer 111 to the external current source (not shown). The
contact hole 141 is formed through the second electrode layer 120 between
the first electrode layer 140 and the second conductivity type
semiconductor layer 113, the second conductivity type semiconductor layer
113, and the active layer 112, and extends to the first conductivity type
semiconductor layer 111. Further, the contact hole 141 is formed of an
electrode material.

[0065]When the contact hole 141 is only used for the electrical
connection, the first electrode layer 140 may include one contact hole
141. However, in order to uniformly spread a current that is transmitted
to the first conductivity type semiconductor layer 111, the first
electrode layer 140 may include a plurality of contact holes 141 at
predetermined positions.

[0066]The conductive substrate 150 is formed in contact with and is
electrically connected to the first electrode layer 140. The conductive
substrate 150 may be a metallic substrate or a semiconductor substrate.
When the conductive substrate 150 is formed of metal, the metal may be
any one of Au, Ni, Cu, and W. Further, when the conductive substrate 150
is the semiconductor substrate, the semiconductor substrate may be formed
of any one of Si, Ge, and GaAs. The conductive substrate 150 may be a
growth substrate. Alternatively, the conductive substrate 150 may be a
supporting substrate. After a non-conductive substrate, such as a
sapphire substrate having small lattice-mismatching, is used as a growth
substrate, and the non-conductive substrate is removed, the supporting
substrate is bonded.

[0067]When the conductive substrate 150 is the supporting substrate, it
may be formed by using a plating method or a substrate bonding method.
Specifically, examples of a method of forming the conductive substrate
150 in the semiconductor light emitting device 100 may include a plating
method of forming a plating seed layer to form a substrate and a
substrate bonding method of separately preparing the conductive substrate
150 and bonding the conductive substrate 150 by using a conductive
adhesive, such as Au, Au--Sn, and Pb--Sr.

[0068]FIG. 3 is a plan view illustrating the semiconductor light emitting
device 100. The via hole 114 is formed in an upper surface of the
semiconductor light emitting device 100, and the electrode pad unit 160
is positioned at the exposed region of the second electrode layer 120. In
addition, though not shown in the upper surface of the semiconductor
light emitting device 100, in order to display the positions of the
contact holes 141, the contact holes 141 are shown as a dotted line to
display the positions of the contact holes 141. The first insulating
layer 130 may extend and surround the contact hole 141 so that the
contact hole 141 is electrically separated from the second electrode
layer 120, the second conductivity type semiconductor layer 113, and the
active layer 112. This will be described in more detail with reference to
FIGS. 4B and 4C.

[0069]FIG. 4A is a cross-sectional view illustrating the semiconductor
light emitting device, shown in FIG. 3, taken along the line A-A'. FIG.
4B is a cross-sectional view illustrating the semiconductor light
emitting device, shown in FIG. 3, taken along the line B-B'. FIG. 4c is a
cross-sectional view illustrating the semiconductor light emitting
device, shown in FIG. 3, taken along the line C-C'. The line A-A' is
taken to show a cross section of the semiconductor light emitting device
100. The line B-B' is taken to show a cross section that includes the
contact holes 141 and the via hole 114. The line C-C' is taken to show a
cross section that only includes the contact holes 141. Hereinafter, the
description will be described with reference to FIGS. 4A to 4C.

[0070]With reference to FIG. 4A, neither the contact hole 141 nor the via
hole 114 is shown. Since the contact hole 141 is not connected by using a
separate connecting line but electrically connected by the first
electrode layer 140, the contact hole 141 is not shown in the cross
section in FIG. 3.

[0071]Referring to FIGS. 4B and 4C, the contact hole 141 extends from the
interface between the first electrode layer 140 and the second electrode
layer 120 to the inside of the first conductivity type semiconductor
layer 111. The contact hole 141 passes through the second conductivity
type semiconductor layer 113 and the active layer 112 and extends to the
first conductivity type semiconductor layer 111. The contact hole 141
extends at least to the interface between the active layer 112 and the
first conductivity type semiconductor layer 111. Preferably, the contact
hole 141 extends to part of the first conductivity type semiconductor
layer 111. However, the contact hole 141 is used for the electrical
connection and current spreading. Once the contact hole 141 is in contact
with the first conductivity type semiconductor layer 111, the contact
hole 141 does not need to extend to the outer surface of the first
conductivity type semiconductor layer 111.

[0072]The contact hole 141 is formed to spread the current in the first
conductivity type semiconductor layer 111. Therefore, a predetermined
number of contact holes 141 are formed, and each of the contact holes 141
has an area small enough to allow uniform current spreading in the first
conductivity type semiconductor layer 111. A small number of contact
holes 141 may cause deterioration in electrical characteristics due to
difficulties in performing current spreading. A large number of contact
holes 141 may cause difficulties in forming the contact holes 141 and a
reduction in light emitting area due to a decrease in area of the active
layer. Therefore, each of the contact holes 141 is formed to have as
small area as possible and allow uniform current spreading.

[0073]The contact hole 141 extends from the second electrode layer 120 to
the inside of the first conductivity type semiconductor layer 111. Since
the contact hole 141 is formed to spread the current in the first
conductivity type semiconductor layer, the contact hole 141 needs to be
electrically separated from the second conductivity type semiconductor
layer 113 and the active layer 112. Therefore, preferably, the contact
hole 141 is electrically separated from the second electrode layer 120,
the second conductivity type semiconductor layer 113, and the active
layer 112. Therefore, the first insulating layer 130 may extend while
surrounding the contact hole 141. The electrical separation may be
performed by using an insulating material, such as a dielectric.

[0074]In FIG. 4B, the exposed region of the second electrode layer 120 is
formed so that the second electrode layer 120 is electrically connected
to the external current source (not shown). The electrode pad unit 160
may be positioned at the exposed region. At this time, a second
insulating layer 170 may be formed on an inner surface of the via hole
114 so that the light emitting lamination 110 and the electrode pad unit
160 can be electrically separated from each other.

[0075]As shown in FIG. 4A, since the first electrode layer 140 and the
second electrode layer 120 are formed in the same plane, the
semiconductor light emitting device 100 has characteristics of the
horizontal semiconductor light emitting device 100. As shown in FIG. 4B,
since the electrode pad unit 160 is formed at the surface of the second
conductivity type semiconductor layer 120, the semiconductor light
emitting device 100 can have characteristics of the vertical light
emitting device. Therefore, the semiconductor light emitting device 100
has a structure into which the vertical structure and the horizontal
structure are integrated.

[0076]In FIGS. 4A to 4C, the first conductivity type semiconductor layer
111 may be an n-type semiconductor layer, and the first electrode layer
140 may be an n-type electrode. In this case, the second conductivity
type semiconductor layer 113 may be a p-type semiconductor layer, and the
second electrode layer 120 may be a p-type electrode. Therefore, the
first electrode layer 140 formed of the n-type electrode and the second
electrode layer 120 formed of the p-type electrode may be electrically
insulated from each other with the first insulating layer 130 interposed
therebetween.

[0077]FIG. 5 is a view illustrating light emission in a semiconductor
light emitting device having an irregular pattern formed at the surface
thereof according to an exemplary embodiment of the present invention.
The description of the same components that have already been described
will be omitted.

[0078]In the semiconductor light emitting device 100 according to the
exemplary embodiment of the invention, the first conductivity type
semiconductor layer 111 forms the outermost edge in a direction in which
emitted light moves.

[0079]Therefore, an irregular pattern 180 can be easily formed on the
surface by using a known method, such as photolithography. In this case,
the light emitted from the active layer 112 passes through the irregular
pattern 180 formed at the surface of the first conductivity type
semiconductor layer 111, and then the light is extracted. The irregular
pattern 180 results in an increase in light extraction efficiency.

[0080]The irregular pattern 180 may have a photonic crystal structure.
Photonic crystals contain different media that have different refractive
indexes and are regularly arranged like crystals. The photonic crystals
can increase light extraction efficiency by controlling light in unit of
length corresponding to a multiple of a wavelength of light.

[0081]FIG. 6 is a view illustrating a second electrode layer exposed at
the edge of a semiconductor light emitting device according to another
exemplary embodiment of the present invention.

[0082]According to another exemplary embodiment of the present invention,
a method of manufacturing a semiconductor light emitting device is
provided. The method includes sequentially laminating a first
conductivity type semiconductor layer 211, an active layer 212, a second
conductivity type semiconductor layer 213, a second electrode layer 220,
an insulating layer 230, a first electrode layer 240, and a conductive
substrate 250; forming an exposed area at the interface between the
second electrode layer 220 and the second conductivity type semiconductor
layer 213; and forming at least one contact hole 241 in the second
conductivity type semiconductor layer 213, the contact hole 241
electrically connected to the first conductivity type semiconductor layer
211, electrically insulated from the second conductivity type
semiconductor layer 213 and the active layer 212, and extending from one
surface of the first electrode layer 240 to at least part of the first
conductivity type semiconductor layer 211.

[0083]At this time, the exposed area of the second electrode layer 220 may
be formed by forming the via hole 214 in a light emitting lamination 210
(refer to FIG. 2). Alternatively, as shown in FIG. 6, the exposed area of
the second electrode layer 220 may be formed by mesa etching the light
emitting lamination 210. In this embodiment, the description of the same
components as those of the embodiment that has been described with
reference to 2 will be omitted.

[0084]Referring to FIG. 6, one edge of a semiconductor light emitting
device 200 is mesa etched. The edge of the semiconductor light emitting
device 200 is etched to expose the second electrode layer 220 at the
interface between the second electrode layer 220 and the second
conductivity type semiconductor layer 213. The exposed area of the second
electrode layer 220 is formed at the edge of the semiconductor light
emitting device 200. A process of forming the exposed region at the edge
of the semiconductor light emitting device 200 is simpler than the
process of forming the via hole in the above-described embodiment, and
also allows a subsequent process of electrical connection to be easily
performed.

[0085]FIG. 7 is a cross-sectional view illustrating a semiconductor light
emitting device package 300 according to still another embodiment of the
present invention. The semiconductor light emitting device package 300
includes a semiconductor light emitting device package body 360a, 360b,
and 360c having an upper surface in which a recessed part is formed, a
first lead frame 370a and a second lead frame 370b mounted to the
semiconductor light emitting device package body 360a, 360b, and 360c,
exposed at a lower surface of the recessed part, and separated from each
other by a predetermined distance, and a semiconductor light emitting
device 310 and 320 mounted to the first lead frame 370a. The
semiconductor light emitting device 310 and 320 is the semiconductor
light emitting device having the via hole at the center thereof according
to the exemplary embodiment of the invention that has been described with
reference to FIG. 2. The description of the same components having been
described will be omitted.

[0086]The semiconductor light emitting device 310 and 320 includes a light
emitting unit 310 and a conductive substrate 320. The light emitting unit
310 includes first and second semiconductor layers, an active layer, and
electrode layers. A via hole is formed in the light emitting unit 310,
and the semiconductor light emitting device 310 and 320 further includes
an electrode pad unit 330 at an exposed region. The conductive substrate
320 is electrically connected to the first lead frame 370a, and the
electrode pad unit 330 is electrically connected to the second lead frame
370b by a wire 340 or the like.

[0087]The semiconductor light emitting device 310 and 320 is electrically
connected to the second lead frame 370b, to which the semiconductor light
emitting device 310 and 320 is not mounted, by wire bonding 340.
Therefore, the semiconductor light emitting device can obtain high
luminous efficiency and has a vertical structure. As shown in FIG. 7, the
semiconductor light emitting device is mounted to the lead frame 370a by
die bonding and to the lead frame 370b by wire bonding. Therefore, the
process can be performed at relatively low costs.

[0088]FIG. 8 is a graph illustrating the relationship between luminous
efficiency and current density of a light emitting surface. When current
density is about 10A/cm2 or more, if the current density is low,
luminous efficiency is high, and if the current density is high, luminous
efficiency is low.

[0089]The relationship between the current density and the luminous
efficiency, and light emitting area are numerically shown in Table 1.

[0090]Referring to FIG. 8 and Table 1, as the light emitting area
increases, luminous efficiency increases. However, in order to ensure the
light emitting area, the area of the distributed electrodes needs to be
reduced, which reduces current density of the light emitting surface. The
reduction in current density of the light emitting surface may
deteriorate electrical characteristics of the semiconductor light
emitting device.

[0091]However, this problem can be solved by ensuring current spreading by
using contact holes according to the embodiments of the invention.
Therefore, the deterioration in electrical characteristics that may be
caused by the reduction in current density can be prevented by using a
method of forming contact holes in the semiconductor light emitting
device that do not extend to the light emitting surface for current
spreading but are formed therein. Therefore, the semiconductor light
emitting device according to the embodiments of the invention performs
desired current spreading and ensures a maximum light emitting area to
obtain desirable luminous efficiency.

[0092]As set forth above, according to exemplary embodiments of the
invention, the semiconductor light emitting device can prevent emitted
light from being reflected or absorbed by electrodes and ensure the
maximum light emitting area by forming the electrodes of semiconductor
layers, located in a light emitting direction, below an active layer
except for part of the electrodes, thereby maximizing luminous
efficiency.

[0093]Further, at least one contact hole is formed in the electrode to
smoothly perform current spreading, such that uniform current spreading
can be performed with the electrode having a small area.

[0094]Further, since the via hole is formed at the upper surface of the
semiconductor light emitting device, alignment is not required during die
bonding, and wire bonding can be easily performed. In addition, since the
semiconductor light emitting device has a vertical structure, wire
bonding and die bonding that can be easily performed at low cost can be
used together when manufacturing a package. Therefore, mass production
can be achieved at low cost.

[0095]Therefore, according to the embodiments of the invention, mass
production of light emitting devices at low cost with high reliability
and high quality can be realized.

[0096]While the present invention has been shown and described in
connection with the exemplary embodiments, it will be apparent to those
skilled in the art that modifications and variations can be made without
departing from the spirit and scope of the invention as defined by the
appended claims.